# cnd_signal

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< c‎ | thread

Defined in header ``<threads.h>`` |  |
int cnd_signal( cnd_t *cond ); |  | (since C11)

Unblocks one thread that currently waits on condition variable pointed to by `cond`. If no threads are blocked, does nothing and returns `thrd_success`.

### Parameters

cond | - | pointer to a condition variable

### Return value

thrd_success if successful, thrd_error otherwise.

### References

- C17 standard (ISO/IEC 9899:2018):

  - 7.26.3.4 The cnd_signal function (p: 276)

- C11 standard (ISO/IEC 9899:2011):

  - 7.26.3.4 The cnd_signal function (p: 379)

### See also

cnd_broadcast (C11) | unblocks all threads blocked on a condition variable (function)
C++ documentation for condition_variable::notify_one
C++ documentation for condition_variable_any::notify_one

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